Device for tilting sewing machine hooks to facilitate threading

ABSTRACT

A device for selectively displacing sewing machine hooks to a position whereat they are readily accessible to an operator for threading purposes. The device includes a lever member pivotably mounted on the shaft which supports the hooks and an arm in the form of a cylindrical seat fixed on the shaft which carries a spring biased pin that is continuously urged into driving engagement with the lever member to effect oscillating movement of the shaft. A manually operable member is provided for disengaging the pin from driving engagement with the lever which permits the shaft to be rotated to a position that places the hooks carried thereby in an accessible position.

BACKGROUND OF THE INVENTION

The present invention relates to a device for tilting sewing machinehooks to facilitate the threading operation.

In addition to the normal upper sewing elements, conventional sewingmachines which sew one or more parallel chain-stitched seams are alsoprovided with one or more hooks which are displaced in a longitudinalmovement at right angles to the direction of advancement of the articlebeing sewn and in a transversal movement parallel to the direction ofadvancement.

In the case of multi-needle chain-stitch sewing machines, the number ofhooks corresponds to the number of needles and they can be disposedeither parallel to the direction of advancement or transversallythereto.

In the case of the known types of multi-needle sewing machines,considerable difficulty has been experienced in threading the hooks,either because the latter, for reasons of space, are completely orpartially concealed by other parts of the machine or because they aredisposed side by side in a position which is not easily accessible tothe operator.

This difficulty is most aggravated in sewing machines provided with fourneedles, wherein one of the most commonly employed hook arrangements isthat known as the "tandem" arrangement in which the hooks are mountedside by side in pairs and in two separate planes on a shaft pivotingabout its own axis and which are disposed transversally relative to thedirection of advancement of the article being sewn.

With conventional four needle sewing machines having the tandem hookarrangement, considerable difficulty has been experienced in threadingthe hooks, particularly the rear hooks, as they are practicallyconcealed by the front hooks.

A considerable amount of time is lost in threading the hooks whichresults in what is considered a substantial loss in production with thistype of sewing machine.

To simplify respresentation thereof, and for purpose of brevity specificreference will only be made hereinafter to a machine having two hooks.

OBJECT OF THE INVENTION

The object of the present invention is to provide a means which willfacilitate the threading of the hooks, and reduce the time required forthis operation.

The technical problem to be solved is that of being able to bring thehooks into a forward position whereat they are readily accessible to theoperator for the purpose of carrying out the threading operation bysimply tilting the hooks per se towards the operator, and of being ableto return the hooks to their operating position after they have beenthreaded, without requiring any special mechanical operations.

SUMMARY OF THE INVENTION

The above technical problem is solved by the device according to thepresent invention which is adapted to tilt the hooks of a sewing machinewhich permits displacement of the hooks in a longitudinal direction atright angles to the direction of advancement of the article to be sewnas well as displacement of the hooks in a transversal direction parallelto the direction of advancement of said article. These hooks aresupported on an oscillatable hook supporting shaft and the deviceincludes a member pivotally mounted on the supporting shaft and anelement fixed on means pivotable about a hook-bearing pivoting shaft, anelement integral with said shaft for movement therewith. A selectivelyreleasable connection means is adapted to rigidly connect the pivotallymounted member to the element fixed on the shaft which is caused topivot on its axis. A retaining means operatively associated with theconnection means permits the latter to be released only when theconnection means is located is a position corresponding to that of theupper needle position.

In addition to rendering the hooks easily accessible for the purpose ofthreading the same, the device according to the invention also has theadvantage of preventing the needles from being stressed or broken as aresult of the hooks striking against the needles, should the hooks bemoved into the threading position when the needles are disposed at thelower portion of their stroke.

These and other features of the invention will be made apparent in thecourse of the following detailed description of two preferredembodiments thereof, provided by way of non-limitative examples and withreference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial front view of a sewing machine equipped with a firstembodiment of a device according to the invention;

FIG. 2 is a plan view of part of the sewing machine showing a section ofonly the device according to the invention along line II--II in FIG.1;

FIG. 3 shows a partial sectional side view of the sewing machine alongline III--III in FIG. 2;

FIG. 4 shows the same side view of the sewing machine according to FIG.3 equipped with a second embodiment of the device according to theinvention;

FIG. 5 is a partial side view of the positions of the hooks in theiroperating position and in the threading position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 the sewing machine equipped with the deviceaccording to the invention includes two needles 1 supported by a clamp 2that is attached to the lower end of a needle bar 3 slidably mounted inthe head 4 which is supported in a projecting manner by a conventionalarm (not shown). This arm is supported by an upright that is connectedto the base 5 which accommodates, inter alia, two hooks 6 and 7 and theassociated operating means.

The hooks 6 and 7 are mounted on supports 8 and 9 respectively, whichare disposed transversally to the direction of advancement of aworkpiece as indicated by line 10 in FIG. 2.

The supports 8 and 9 are pivotally mounted at 11 and 12 respectively, ona sleeve 13 and are interconnected in a conventional manner by aconnecting rod 14 (FIG. 1).

The sleeve 13 is fixed on an oscillatable hook supporting shaft 15 theends of which are journalled in spaced walls 16 and 17 that extendupwardly from the base 5 of the machine.

The head 19 of a rod 20 is connected to the support 8 by means of aspherical pin 18. The rod 20 extends through an oil sleeve 21 and beyondwall 17 where it is connected by means of a head 22 and spherical pin 23to a lever 24. The lower end of lever 24 is fixed, as shown in FIG. 1,to an oscillatably driven shaft 25.

The oscillating movement of the shaft 25 is effected by conventionalmeans (not shown) from the main shaft 26 which in a known manner isrotatably driven.

The rod thus causes the hooks to reciprocate in a longitudinal directionperpendicular to the direction of advancement indicated by numeral 10 inFIG. 2.

As is more clearly shown in FIG. 3, an eccentric 27 is fixed on the mainshaft 26 and includes an associated lever 28 pivotally connected at 29to an arm 30 of a double armed lever 31 that is pivotably mounted on theshaft 15. This lever 31 constitutes a pivoting means and is providedwith another arm 32 having a segment 33 disposed coaxial to the axis ofthe shaft 15 which includes a radial bore 34, into which the tip 35 of apin 36 is insertable. Pin 36 is slidably carried within an actuatingmeans that defines a cylindrical seat 37 and is biased in the directionof the radial bore by a coil spring 38 as shown in FIG. 2.

The end of the cylindrical seat 37, from which the pin 36 projects, hasthe same curvature as the segment 33, and the opposite end defines aclamp 39 which is tightened by means of a screw 40 on the shaft 15. Thecylindrical seat 37 also includes a longitudinal slot 41 from which astem 42 extends. One end of this stem 42 is attached to the pin 36 andthe opposite end has a knob 43 assembled thereon.

A support bracket 45 is attached to the base of the machine by means ofscrews 44. A plate 47 is adjustably attached to the upper end of thesupport bracket 45 and includes an open slot 48 within which the stem 42is adapted to pivot. The opening into the open slot 48 is identified bynumeral 49 and is of a size approximately equal to the diameter of thestem 42.

The device according to the invention operates in the following manner.When it is necessary to thread the hooks, the knob 43 is pushed toovercome the biasing force of spring 38, and until the tip 35 of the pin36 is moved out of the bore 34 of the segment 33.

At this point, the sleeve 13 and thus the hook supports are free torotate towards the outside of the machine as shown in FIG. 5, in whichthe two hooks 6 and 7 are shown in their operating position and the samehooks, designated by 6' and 7', are shown in the threading positionwhereat they are disposed in a position accessible to the operator.

The hooks are pivoted by the operator to the threading position afterthe tip 35 has been disengaged from the segment 33. This is facilitatedowing to the fact that the hooks are being moved relative to the axis ofthe shaft 15 and they tend to rotate through the action of gravity. Thedisplacement of the pin 36 in the cylindrical seat 37 is only possiblewhen the stem 42 is in a position that is in alignment with the opening49. Obtaining this position is only possible when the needles of thesewing machine are located at the upper end of their stroke. The needlebar 3 is operatively connected to the shaft 15 by conventional means(not shown) that are actuated by the main shaft 26.

When the needles are in any other position the stem 42 is engaged in theopen slot 48 and thus the pin 36 cannot be displaced which prevents thehooks from being tilted towards the outside of the machine.

The hooks can only be tilted when the needles are located at the upperend of their stroke for any other position would create an interferencewhen attempting to tilt the hooks that could result in either damage toor breakage of the needles.

After the hooks have been threaded, they are pushed back manuallytowards their operating position until the tip 35 sliding along thesegment 33 again enters the bore 34. A stop 50 (FIG. 3) is provided onthe upper part of the segment 33 to restrict movement of the cylindricalseat 37 and prevent the tip 35 from missing the bore 34 as a result ofan over rapid movement of the hooks.

A modification of the invention is shown in FIG. 4 which includes asupport bracket fixedly mounted on the sewing machine base. This supportbracket 51 is provided with a bore 52 within which a pin 53 having apush knob 54 and a return spring 55 is adapted to slide.

The pin 53 is coaxial with the tip 35 of the pin 36 (FIG. 2) only whenthe needles are situated at the upper end of their stroke and thus bypressing on the push knob 54 it can be pressed against tip 35 until itis removed from the bore 34 of the segment 33.

Although the present invention has been described in connection with apreferred embodiment, it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and the appended claims.

I claim:
 1. A device for tilting the hooks within the base of a sewingmachine of the type having needles operatively associated with the hooksfor forming chain stitches, said device comprising:a. a hook supportingshaft (15) oscillatably supported within the base of the sewing machine;b. a lever member (31) pivotally mounted on said hook supporting shaftwhich includes:i. an arm (32) having a segment (33) formed on the freeend thereof, said segment being concentric to said hook supporting shaft(15) and including means on the inner surface thereof defining a radialbore (34); c. actuating means (37) fixed on said hook supporting shaftin operative association with said lever member; d. a pin (36) slidablycarried by said actuating means for connecting said lever member (31)with said actuating means (37) to effect oscillating movement of saidhook supporting shaft (15); and e. means for selectively disconnectingsaid lever member (31) from said actuating means (37) to permit tiltingof the hooks to a position to facilitate the threading thereof.
 2. Thedevice according to claim 1 wherein said actuating means (37) defines acylindrical seat within which said pin (36) is slidably assembled. 3.The device according to claim 2 wherein said pin includes a tip (35) anda coil spring (38) operatively associated with said pin for continuouslyurging said tip (35) in the direction of said radial bore (34).
 4. Thedevice according to claim 3 wherein said disconnecting means includes astem (42) fixed to and extending from said pin (36) in a plane normal tothe axis thereof for selectively moving said tip (35) out of said radialbore (34) when the needles are located at the upper end of their stroke.5. The device according to claim 3 wherein said disconnecting meansincludes a spring biased pin (53) selectively movable in a longitudinaldirection, when the needles are located at the upper end of theirstroke, to engage and move said tip (35) out of said radial bore (34).